Bandwidth Allocation in Fixed Broadband Wireless Networks

Abstract

We consider use of fixed broadband wireless networks to provide packet services for telecommuting and Internet access. Each cell in such networks is divided into multiple sectors, each of them served by a sector antenna co-located with the base station (BS), and user terminals also use directional antennas mounted on the roof top of homes or small offices and pointed to their respective BS antennas. To support a target data rate of 10 Mb/s, a bandwidth of several MHz is required. Since radio spectrum is expensive, the bandwidth need to be reused very aggressively. Thus, efficient strategies for frequency reuse and managing co-channel interference are critically important. We propose here a dynamic radio-resource allocation method, to be referred to as staggered resource allocation (SRA) method, that uses a distributed scheduling algorithm to avoid major sources of interference, while allowing concurrent packet transmission and meeting a specified signal-to-interference objective. The performance of the method is studied by analytic approximations and detailed simulation. Our results show that the combination of directional antennas plus the SRA method is highly effective in controlling co-channel interference. For reasonable system parameters, the SRA method delivers a throughput in excess of 30% per sector while permitting a given frequency band to be re-used in every sector of every cell. It also provides higher than 90% probability of successful packet transmission at appropriate traffic load conditions. In addition, a simple control mechanism can be applied in the method to improve performance for harsh radio environments.